Match the order given in column (I) with the property(les) in column (II).
`{:("Column I","Column II"),((A)Rb_2CO_3gtK_2CO_3gtNa_2CO_3,(p)"Solubility of salts in water"),((B)SrSO_4gtCaSO_4gtMgSO_4,(q)"Thermal stability of salts"),((C )RbgtKgtNa,(r)"Softness of metals"),((D)BegtMggtCa,(s)"Hydration energy of metals"),(,(t)"Ionisation energy of metals "):}`

Explanation

To solve the problem of matching the orders given in Column (I) with the properties in Column (II), we will analyze each option step by step.

### Step 1: Analyze Column (I) - Part A
**A: Rb₂CO₃ > K₂CO₃ > Na₂CO₃**
- These are alkali metal carbonates.
- The solubility of alkali metal carbonates in water increases down the group (from Na to Rb) due to the decrease in lattice energy being greater than the decrease in hydration energy.
- **Match:** A → P (Solubility of salts in water)

### Step 2: Analyze Column (I) - Part B
**B: SrSO₄ > CaSO₄ > MgSO₄**
- These are alkaline earth metal sulfates.
- The solubility of alkaline earth metal sulfates decreases down the group due to the decrease in hydration energy.
- **Match:** B → Q (Thermal stability of salts)

### Step 3: Analyze Column (I) - Part C
**C: Rb > K > Na**
- This refers to the softness of metals.
- As we move down the group, the metallic bonding decreases, leading to increased softness.
- **Match:** C → R (Softness of metals)

### Step 4: Analyze Column (I) - Part D
**D: Be > Mg > Ca**
- This compares beryllium, magnesium, and calcium.
- The hydration energy decreases down the group, but the ionization energy also decreases.
- **Match:** D → S (Hydration energy of metals)

### Final Matches:
- A → P (Solubility of salts in water)
- B → Q (Thermal stability of salts)
- C → R (Softness of metals)
- D → S (Hydration energy of metals)

### Summary of Matches:
- A: P
- B: Q
- C: R
- D: S